Rental Cash Flow Calculator
See a rental true monthly cash flow after the mortgage, vacancy, and every operating expense, so you know if it pays for itself.
Want to understand the concept, not just the number? Read The Real Estate Investing Guide .
How it's calculated
Cash flow is the number that keeps a rental alive. It is simply the rent you actually collect, minus everything you have to pay each month. Positive cash flow means the property pays for itself and puts money in your pocket. Negative cash flow means you feed it out of your own income every month, betting on appreciation to make up for it.
Work through the default. Rent is $2,200 a month, but a 5 percent vacancy allowance for empty months brings the collected amount to $2,090. The mortgage on a $200,000 loan at 7 percent over 30 years is $1,330.60 in principal and interest. Then the operating expenses, property tax of $250 a month, insurance of $100, a $150 maintenance reserve, and $175 for management, add up to $675. Subtract the $1,330.60 mortgage and the $675 of expenses from the $2,090 of collected rent, and the property clears $84.40 a month, or about $1,013 a year.
That is a thin margin, and it shows how quickly a rental can slip into the red at today rates. A single repair or an extra vacant month can wipe out a year of it. The levers that help most are a larger down payment to shrink the mortgage, a lower purchase price, higher rent, or self-managing to cut the management fee. Always keep a real vacancy and maintenance reserve in the numbers, since a property that only cash flows when nothing goes wrong is not really cash flowing.
Assumptions
- Cash flow is the rent after a vacancy allowance, minus the mortgage payment and every operating expense you enter.
- The mortgage is principal and interest only, since tax and insurance are entered separately. A fixed rate compounded monthly.
Last updated: 2026-08-08
These assumptions follow our general methodology.
Frequently asked questions
What is good monthly cash flow for a rental?
Many investors want at least $100 to $200 per unit per month after every expense, including reserves. The right target depends on your market and how much you expect from appreciation, but a deal should clear a real cushion once vacancy and maintenance are counted, not just break even on a perfect month.
Why is my rental cash flow negative?
Usually a high mortgage rate, a small down payment, or a purchase price that is high relative to rent. In many markets today, a 20 to 25 percent down payment is not enough to cash flow, so buyers either put more down, negotiate the price, or accept that the return rides on appreciation and loan paydown instead.
Should I count vacancy and maintenance if my unit is full and new?
Yes. Vacancy and repairs are not if, they are when. Leaving them out makes a marginal deal look healthy, then the first empty month or roof repair turns the real cash flow negative. A 5 percent vacancy allowance and a maintenance reserve keep the number honest.
How can I improve cash flow on a property I already own?
Raise rent toward market at renewal, appeal a high property tax assessment, shop your insurance, self-manage if the fee is large, or refinance if rates have fallen. On the buy side, a larger down payment or a lower price does the most, since the mortgage is usually the biggest single cost.